This invention relates to treatment of used lubricating oils.
In one of its aspects this invention relates to the removal of impurities of used lubricating oils. In another of its aspects this invention relates to the removal of additive systems from used lubricating oils to provide a lube oil stock. In another aspect of the invention it relates to removal and separation of specific contaminants such as gasoline, metal components, and nitrogen, sulfur and oxygen compounds in a process for treating used lubricating oils. In still another aspect of the invention it relates to facilitating the separating of the oil phase from residual product in the treatment of used lubricating oils.
In recent years the performance of lubricating oils has been greatly improved by the addition of a number of compounds such as detergents, pour point depressants, oxidation inhibitors and viscosity index improvers. The purpose of using modern detergent additives, such as calcium and barium salts of alkyl benzene sulfonic acids and ashless type detergents such as alkyl-substituted succinimides, is to suspend the resins that normally form in oil while in use as well as carbon, dirt, wear metals and other impurities in the oil in the engine so that these suspended impurities remain with oil drained from the engine during oil changes and are eliminated in this manner.
The presence of the suspended impurities and the engine additives has greatly increased the task of reclaiming the used engine oils. The problem is accentuated by the presence of oil from diesel engines in mixtures of used engine oils. These oils, probably because of additional carbon or soot, are particularly difficult to filter after treatment which precipitates other impurities from the used oil. It has now been discovered that the presence of certain polyhydroxy compounds in the reaction mixture for the treatment of used lubricating oil with an aqueous ammonium salt treating agent facilitates the filtering of the precipitate produced by the reaction of used oil and the treating agent.
Since service stations tend to place all crank case drainings into a common tank practically all lubricating oil available for re-refining or reclaiming processes has not only high-detergency properties, but also contains crank case drainings from diesel engines. The present invention allows more efficient treating of crank case drainings received in large lots by re-refining or reclaiming processers.
It is, therefore, an object of this invention to provide a means for facilitating the filtration step in a universally applicable system for reclaiming used lubricating oils.
It is another object of this invention to provide improved filtration in an integrated process for reclaiming a high-purity lube oil stock from high-detergent-containing used lubricating oils.
It is another object of this invention to provide a process for efficiently treating used oils containing diesel engine crank case oil.
Other aspects, objects and the advantages of this invention will be apparent to one skilled in the art upon studying this disclosure, the appended claims and the drawing which is a schematic representation of the process of this invention.